(1) Field of the Invention
The present invention relates to a device and method for testing the operation of communication networks, specifically MS-SPRING optical fiber communication networks, which provides for traffic protection means (Multiplexed-Shared Protection Ring).
(2) Description of the Prior Art
In present telecommunication networks it has become extremely important to be able to restore failures occurring in said networks without jeopardizing their service function.
For this reason, telecommunication networks, specifically optical fiber networks, are equipped with protection means to protect them against any failure of the network elements.
In MS-SPRING networks a distributed protection mechanism is implemented for automatically restoring the traffic in case of any defects in the connecting fibers.
MS-SPRING networks perform the automatic traffic restoring through a synchronized rerouting of said traffic which is carried out at each ring node. This operation is controlled by a protocol consisting of 16-bit configured patterns, which are continuously exchanged between adjacent nodes. Said protocol and the operations involved thereby with reference to the different bit patterns are defined by many international standards issued by ANSI, ITU-T and ETSI.
To this purpose, reference is made for instance to xe2x80x98CCITT Recommendation G 841, Draft, April 1995xe2x80x99, xe2x80x98ETSI DTR TM-03041, September 1995xe2x80x99, xe2x80x98ANSI T1-105-1998xe2x80x99.
The standards define two kinds of MS-SPRING networks, one for two-fiber rings, i.e. each ring node is connected with another node by a span consisting of two optical fibers conveying signals propagating in opposite directions, the other one for four-fiber rings able of conveying a higher amount of traffic.
FIG. 1 shows a MS-SPRING two-fiber network ring 1. Said ring 1 consists of a set of 6 network elements or nodes NE. In general, network elements NE can be in number of 2 to 16. Each network element NE has two bi-directional communication ports PO, i.e. each port operates both for transmission and reception. One communication port PO is dedicated for clockwise traffic E and the other for counter-clockwise traffic W.
Two adjacent network elements NE are joined together by a span SP, which span SP consists of two connections CN, each of them obtained by an optical fiber and conveying traffic in opposite directions, i.e. one in clockwise direction E and the other one in counter-clockwise direction W.
In order to provide protection without affecting too much the bandwidth usage, the bandwidth in the MS-SPRING network ring 1 is split in two halves of equal capacity, designated work capacity and protection capacity. Work capacity is used for high priority traffic, whereas protection capacity is used for low priority traffic, the latter going lost in case of failure.
Protection in MS-SPRING network ring 1 is implemented according to a so-called Bridge-and-Switch technique, consisting essentially in re-routing traffic from work capacity to protection capacity in opposite direction through a proper change of the network element internal connections.
Such a protection technique, designated APS (Automatic Protection Switch), requires for each network element to contain a device, designated APS controller, which is capable of detecting line failures, communicating information related to the other network elements and performing Bridge-and Switch type switching.
The protection system of a MS-SPRING network, substantially based on said APS controllers, requires execution of tests of said system to check its full functionality. This operation is usually carried out for each new MS-SPRING network version released by the manufacturer, substantially with the aim of testing that the functionality of said system has not been jeopardized by updating operations, i.e. the issue of a new version with new technical capabilities.
This involves several problems, since complexity of tests depends at least on the number of nodes of the network rings to be tested, on the number of stable states the MS-SPRING network may have and which have to be tested, and on the high number of events occurring in a MS-SPRING network, which have to be reproduced during test. Moreover, the operator carrying out such tests is required to transmit a high number of commands and, finally, the test results can only be understood and evaluated by specially trained operators having a wide knowledge of MS-SPRING network features.
It is the object of the present invention to solve the above drawbacks and provide a device or system for testing the operation of MS-SPRING communication networks, having a more effective and improved performance.
In this scenario, it is the main object of the present invention to provide a device or system for testing the operation of communication networks using an automated test apparatus.
Another object of the present invention is to provide a system or device for testing the operation of communication networks, capable of automatically testing different network types without requiring any manual operation by the operator.
Another object of the present invention is to provide a system or device for testing the operation of communication networks having a number of tests whose execution provides significant information about the network function.
A further object of the present invention is to provide a system or device for testing the operation of communication networks having an automatic procedure for test result evaluation.
Said objects are reached by the present invention by a system for testing the operation of communication networks and/or a method for testing the operation of an optical fiber network incorporating the features of the annexed claims, which form an integral part of this description.
Further objects, features and advantages of the present invention will become apparent from the following detailed description and annexed drawings, which are only supplied by way of an explanatory non limiting example.
The device for testing the operation of communication networks, specifically MS-SPRING optical fiber communication networks according to the present invention comprises traffic protection means and further comprises modulation and measurement elements which can be driven by a controller to execute automatic test of the operation of the traffic protection means for one or more rings of the optical fiber communication network.
The method for testing the operation of a MS-SPRING optical fiber network according to the present invention comprises: installing, on one or more rings of the optical fiber, network modulation and measurement elements, which elements can be remote controlled; connecting a controller with said modulation and measurement elements through first interface means, and with network elements of said rings through second interface means, respectively; installing the network of optical switches between the network elements; installing test pattern generators/checkers on the desired network elements; and executing a failure simulation and operation test procedure through the processor.
Finally, the apparatus for testing the operation of an optical fiber network, specifically MS-SPRING, comprises modulation and measurement elements, associated with one or more rings of an optical fiber communication network, which can be controlled by a processor and which simulate failures indicating whether the traffic protection means contained in the communication network are operating.